The present invention relates generally to a filtration apparatus for separating solid particles from a liquid. More particularly, the invention relates to filtration apparatus for removing particulate contaminants from commercial laundry waste water and a method for accomplishing the same.
State and local governments across the country as well as the federal government have enacted environmental laws or expanded existing environmental laws to reverse or limit the threat of environmental pollution. These environmental laws are typically directed toward commercial enterprises which create various wastes streams as a by-product of manufacturing products or providing services. The commercial laundry industry and particularly commercial laundromats are specifically affected by environmental laws which limit the amount of suspended solids or particulate contaminants in commercial laundry waste water which can be discharged into the environment. Particulate contaminants in commercial laundry waste water generally consist of lint, hair, dirt and soap scum. To meet current environmental laws, the amount of particulate contaminants in the commercial laundry waste water must be reduced to an acceptable level before it is discharged into the ground water and/or municipal sewage system.
Separating solid particles, impurities, particulate contaminants, etc. from a liquid or gas is generally accomplished by passing it through a porous substance or a filter. For example, U.S. Pat. No. 4,322,293 granted to Morgan, Jr. discloses a multiple element filter having a housing which supports and suspends a number of filter elements, e.g., screen or cloth or other similar interwoven filtering material, which have open upper ends which accept a liquid to be filtered. However, once the filter elements become clogged or full, the housing must be opened and the filter elements removed and cleaned or replaced.
A number of devices for filtering or separating solid particles, impurities, particulate contaminants, etc. from a liquid include a filter or filter elements and also means for imparting motion to the filter elements to aid in the filtering or separating process and/or removal of separated contaminants from the surface of the filter elements. One example, is U.S. Pat. No. 2,480,320 granted to Carrier which discloses a filter apparatus for removing impurities from cleaning fluids used in dry cleaning clothing. The filter apparatus includes a casing having a plurality of individual filter elements which are vertically supported in spaced relation to each other and in such a way that they can be oscillated in the casing as a unit while in the cleaning liquid to remove sludge from the filter elements whereupon it will drop into the lower portion of the casing below an outlet pipe. At frequent intervals the sludge can be removed through a sludge outlet.
Another example is U.S. Pat. No. 4,289,630 granted to Schmidt, Jr. et al. which discloses a filtration apparatus having a plurality of filter elements supported between an upper inlet manifold and a lower outlet manifold. The filter apparatus also includes means for cleaning the filter element after a filter cake has been deposited thereon. Specifically, a vibratory impactor is mounted on upper inlet manifold to impart vertically directed shock waves to the manifold and to the filter elements connected thereto to dislodge the filter cakes.
Still another example is U.S. Pat. No. 5,350,526 granted to Sharkey, et al., the inventors of the present invention, which disclose a filtration apparatus for removing particulate contaminants from commercial laundry waste water in which the apparatus has at least one porous mesh-like filter bag coupled between an upper inlet manifold for receiving waste water containing particulate contaminants and a lower outlet manifold for discharging the particulate contaminants separated from the waste water. The filtration apparatus also includes a paddle for agitating the filter bag so as to prevent the mesh-like material of the filter bag from becoming clogged.
Also, a number of devices for filtering or separating solid particles, impurities, particulate contaminants, etc., from a liquid include a filter or filter elements and also spray means for aiding in the filtering process and/or removal of accumulated contaminants. For example, U.S. Pat. No. 4,591,446 granted to M uller discloses a pressurized filtering device in which the liquid to be filtered is transferred through a plurality of vertically suspended tube-like filter elements wherein particulate contaminants accumulate on the outer surface to the filter elements. A spray nozzle, located above the filter elements, provides a second operation of rinsing the outer surface of the tube-like filter elements with a combination of a rinsing liquid and pressurized air to remove the particulate contaminants accumulated on the outer surface of the filter element for subsequent discharge of the particulate contaminants out a separate opening at the bottom of the device. Similarly, U.S. Pat. No. 4,213,861 granted to Muller, et al. discloses a plurality of vertically extending spray tubes, disposed adjacent the tube-like filter elements for rinsing out accumulated particulate contaminants on the outer surface of the filter elements.
A filtration device which has a filtering medium and incorporates both hydraulic and mechanical forces during the process of removing accumulated particulate contaminants is U.S. Pat. No. 3,557,955 granted to Hirs, et al. Hirs, et al. discloses a filtration apparatus for removal or relatively small particulate contaminants in which the filtration apparatus includes a filtering medium of finely divided particulate material, e.g., polyvinyl chloride, polyethylene or wood sawdust. Following filtration, the filter medium is back washed. In addition to the hydraulic forces caused due to back washing, agitators located within the filter medium are rotated to apply mechanical forces during back washing to aid in removal of the accumulated particulate contaminants.
Thus, for satisfying the laundry industry, there is a need for a filtration apparatus that is capable of accepting a relatively large flow of laundry water, capable of removing the relatively small suspended particulate contaminants, and capable of continuous automated operation.